Abstract:
:Iron loss in vitro by the iron scavenger bovine lactoferrin was investigated in acidic media in the presence of three different monoanions (NO(3)(-), Cl(-) and Br(-)) and one dianion (SO(4)(2-)). Holo and monoferric C-site lactoferrins lose iron in acidic media (pH< or =3.5) by a four-step mechanism. The first two steps describe modifications in the conformation affecting the whole protein, which occur also with apolactoferrin. These two processes are independent of iron load and are followed by a third step consisting of the gain of two protons. This third step is kinetically controlled by the interaction with two Cl(-), Br(-) and NO(3)(-) or one SO(4)(2-). In the fourth step, iron loss is under the kinetic control of a slow gain of two protons; third-order rate-constants k(2), 4.3(+/-0.2)x10(3), 3.4(+/-0.5)x10(3), 3.3(+/-0.5)x10(3) and 1.5(+/-0.5)x10(3) M(-2) s(-1) when the protein is in interaction with SO(4)(2-), NO(3)(-), Cl(-) or Br(-), respectively. This step is accompanied by the loss of the interaction with the anions; equilibrium constant K(2), 20+/-5 mM, 1.0(+/-0.2)x10(-1), 1.5(+/-0.5)x10(-1) and 1.0(+/-0.3)x10(-1) M(2), for SO(4)(-), NO(3)(-), Cl(-) and Br(-), respectively. This mechanism is very different from that determined in mildly acidic media at low ionic strength (micro<0.5) for the iron transport proteins, serum transferrin and ovotransferrin, with which no prior change in conformation or interaction with anions is required. These differences may result from the fact that in the transport proteins, the interdomain hydrogen bonds that consolidate the closed conformation of the iron-binding cleft occur between amino acid side-chain residues that can protonate in mildly acidic media. With bovine lactoferrin, most of the interdomain hydrogen bonds involved in the C-site and one of those involved in the N-site occur between amino acid side-chain residues that cannot protonate. The breaking of the interdomain H-bond upon protonation can trigger the opening of the iron cleft, facilitating iron loss in serum transferrin and ovotransferrin. This situation is, however, different in lactoferrin, where iron loss requires a prior change in conformation. This can explain why lactoferrin does not lose its iron load in acidic media and why it is not involved in iron transport in acidic endosomes.
journal_name
J Mol Bioljournal_title
Journal of molecular biologyauthors
Abdallah FB,El Hage Chahine JMdoi
10.1006/jmbi.2000.4101keywords:
subject
Has Abstractpub_date
2000-10-20 00:00:00pages
255-66issue
2eissn
0022-2836issn
1089-8638pii
S0022-2836(00)94101-9journal_volume
303pub_type
杂志文章abstract::The purpose of the current study was to alter the broad native tropism of human adenovirus for virus targeting to c-erbB2-positive cancer cells. First, we engineered a single-chain antibody (scFv) against the c-erbB2 oncoprotein into minor capsid protein IX (pIX) of adenovirus serotype 5 (Ad5) in a manner commensurate...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1016/j.jmb.2009.03.016
更新日期:2009-05-08 00:00:00
abstract::Recently, progress has been made toward understanding the functional diversity of bacterial microcompartment (MCP) systems, which serve as protein-based metabolic organelles in diverse microbes. New types of MCPs have been identified, including the glycyl-radical propanediol (Grp) MCP. Within these elaborate protein c...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1016/j.jmb.2014.07.018
更新日期:2014-09-23 00:00:00
abstract::Anthracycline antibiotics daunomycin and adriamycin are among the most widely used in cancer chemotherapy and DNA is believed to be the primary target of their biological action. The crystal structure of a morpholino derivative of adriamycin bound to the DNA hexamer d(CGTACG) has been determined at 1.5 A resolution. T...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1006/jmbi.1993.1208
更新日期:1993-04-05 00:00:00
abstract::A large conformational change is observed between HIV-1 proteinase in the ligand-free state and in complexes with transition-state inhibitors. Crystal structures of this enzyme have either the flaps open for the native or ligand-free enzyme or the flaps closed for peptidomimetic ligand-bound enzyme. We describe the st...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1006/jmbi.1994.1353
更新日期:1994-05-27 00:00:00
abstract::The three-dimensional structure of 2H1, a protective monoclonal antibody to Cryptococcus neoformans, has been solved at 2.4 A resolution, in both its unbound form and in complex with the 12 amino acid residue peptide PA1 (GLQYTPSWMLVG). PA1 was previously identified as a potential mimotope of the cryptococcal capsular...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1006/jmbi.1997.1407
更新日期:1997-12-12 00:00:00
abstract::The transcriptional co-activators CBP/p300 and PCAF participate in transcriptional activation by many factors. We have shown that both CBP/p300 and PCAF stimulate the transcriptional activation by KLF13, a member of the KLF/Sp1 family, either individually or cooperatively. Here we further investigated how CBP and PCAF...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1016/s0022-2836(03)00429-7
更新日期:2003-05-30 00:00:00
abstract::Escherichia coli ribosomal RNA contains five guanosine residues methylated at N2. The ygjO gene was previously predicted to methylate 16 S rRNA residue G966 due to its high sequence homology with the protein RsmC, responsible for G1207 methylation. We have identified the target of YgjO as being m2G1835 of the 23 S rRN...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1016/j.jmb.2006.09.008
更新日期:2006-11-17 00:00:00
abstract::Phage Mu transposes promiscuously, employing protein MuB for target capture. MuB forms stable filaments on A/T-rich DNA, and a correlation between preferred MuB binding and Mu integration has been observed. We have investigated the relationship between MuB-binding and Mu insertion into hot and cold Mu targets within t...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1016/j.jmb.2008.05.032
更新日期:2008-07-18 00:00:00
abstract::The 14-3-3 family of proteins plays a role in a wide variety of cellular functions including regulation of protein kinase C and exocytosis. Using antisera specific for the N termini of 14-3-3 isoforms described previously and an additional antiserum specific for the C terminus of epsilon isoform, protease digestion of...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1006/jmbi.1994.0031
更新日期:1995-01-27 00:00:00
abstract::The folding pathway of human FKBP12, a 12 kDa FK506-binding protein (immunophilin), has been characterised. Unfolding and refolding rate constants have been determined over a wide range of denaturant concentrations and data are shown to fit to a two-state model of folding in which only the denatured and native states ...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1006/jmbi.1999.2941
更新日期:1999-08-13 00:00:00
abstract::The CheY protein is the response regulator in bacterial chemotaxis. Phosphorylation of a conserved aspartyl residue induces structural changes that convert the protein from an inactive to an active state. The short half-life of the aspartyl-phosphate has precluded detailed structural analysis of the active protein. Pe...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1006/jmbi.2000.3595
更新日期:2000-03-31 00:00:00
abstract::The 90-kDa heat shock proteins (Hsp90s) assist the maturation of many key regulators of signal transduction pathways and cellular control circuits like protein kinases and transcription factors and chaperone their stability and activity. In this function, Hsp90s cooperate with some 30 cochaperones and they are themsel...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1016/j.jmb.2017.01.011
更新日期:2017-03-10 00:00:00
abstract::We improved a motility assay system by using an affinity-purified antibody against the C-terminal globular domain of characean myosin. This improvement allowed us to study the sensitivity to ionic strength or the processivity of characean myosin. The sliding velocity of actin filaments on a characean myosin-coated sur...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1016/s0022-2836(02)01469-9
更新日期:2003-02-21 00:00:00
abstract::The three-dimensional structure of a site-directed mutant of the bacterially expressed Fv fragment from monoclonal antibody D1.3, complexed to the specific antigen lysozyme has been determined to a nominal resolution of 1.8 A using X-ray diffraction data. The replacement of VL Trp92 by Asp allows two water molecules t...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1006/jmbi.1994.1309
更新日期:1994-05-13 00:00:00
abstract::PHF1 associates with the Polycomb repressive complex 2 and it was demonstrated to stimulate its H3K27-trimethylation activity. We studied the interaction of the PHF1 Tudor domain with modified histone peptides and found that it recognizes H3K36me3 and H3tK27me3 (on the histone variant H3t) and that it uses the same tr...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1016/j.jmb.2013.08.009
更新日期:2014-04-17 00:00:00
abstract::An alphoid-like human repetitive DNA of the Sau3A family is present extrachromosomally and in the chromosomes. In the chromosomes, the DNA is located on chromosome 11 but related sequences are present in chromosome 17. We characterized the nature of the recombination involved in the excision of the extrachromosomal DN...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1016/0022-2836(87)90202-6
更新日期:1987-12-20 00:00:00
abstract::Site-directed mutations were introduced in the connecting loops and one of the two stem regions of the RNA pseudoknot in the tRNA-like structure of turnip yellow mosaic virus RNA. The kinetic parameters of valylation for each mutated RNA were determined in a cell-free extract from wheat germ. Structure mapping was per...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1016/0022-2836(92)90727-2
更新日期:1992-01-05 00:00:00
abstract::We demonstrate, using transmission electron microscopy and immunopurification with an antibody specific for RNA/DNA hybrid, that intact mitochondrial DNA replication intermediates are essentially duplex throughout their length but contain extensive RNA tracts on one strand. However, the extent of preservation of RNA i...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1016/j.jmb.2010.02.029
更新日期:2010-04-16 00:00:00
abstract::The alcohol dehydrogenase (ADHase) enzyme catalyses the oxidation of alcohols to aldehydes or ketones using NAD+ as a cofactor. Functional ADHase from Drosophila lebanonensis is a dimer, with a monomeric molecular weight of 27,000 and with 254 residues in each polypeptide chain. Crystals of the protein have been grown...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1016/0022-2836(92)90705-o
更新日期:1992-09-05 00:00:00
abstract::Peptides that bind to major histocompatibility complex products (MHC) are known to exhibit certain sequence motifs which, though common, are neither necessary nor sufficient for binding: MHCs bind certain peptides that do not have the characteristic motifs and only about 30% of the peptides having the required motif, ...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1006/jmbi.1997.0937
更新日期:1997-04-18 00:00:00
abstract::Filamentous bacteriophage (Inovirus) is a simple and well-characterized model system. The phage particle, or virion, is about 60 angstroms in diameter and several thousand angstrom units long. The virions are assembled at the bacterial membrane as they extrude out of the host without killing it, an example of specific...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1016/j.jmb.2005.10.048
更新日期:2006-01-13 00:00:00
abstract::Controlled activity of several kinesin motors is required for the proper assembly of the mitotic spindle. Eg5, a homotetrameric bipolar kinesin-5 from Xenopus laevis, can cross-link and slide anti-parallel microtubules apart by a motility mechanism comprising diffusional and directional modes. How this mechanism is re...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1016/j.jmb.2010.03.009
更新日期:2010-05-28 00:00:00
abstract::The innermost chorionic layer (ICL) within egg shells of Drosophila melanogaster is composed of thin, abutting three-dimensional crystalline plates which form a closed, membrane-like sheath. Collectively, the crystals within the sheath appear to form a family of related three-dimensional crystals in space group C222; ...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1016/0022-2836(87)90350-0
更新日期:1987-02-20 00:00:00
abstract::A method using binding site "neighbor-effect" parameters (NEPs) is introduced to evaluate the effects of interaction between adjacent ligands on their binding to an infinite linear lattice. Binding site overlap is also taken into account. This enables the conditional probability approach of McGhee & von Hippel to be e...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1016/0022-2836(92)90262-i
更新日期:1992-02-20 00:00:00
abstract::The crystal structures of adenylate kinases from the thermophile Methanococcus thermolithotrophicus and the mesophile Methanococcus voltae have been solved to resolutions of 2.8A and 2.5A, respectively. The structures of the enzymes are similar to that of the adenylate kinase from archaeal Sulfolobus acidocaldarius in...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1016/s0022-2836(03)00655-7
更新日期:2003-07-25 00:00:00
abstract::We describe fibre diffraction studies on the interaction of DNA with different amino acids and peptides. The B form of DNA, with ten base-pairs per turn, is always found at high levels of humidity. We suggest that this pitch is observed because the DNA molecules are maintained in a straight position. In solution, the ...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1016/0022-2836(86)90444-4
更新日期:1986-02-05 00:00:00
abstract::The pre-tRNA processing enzyme ribonuclease P is a ribonucleoprotein. In Escherichia coli assembly of the holoenzyme involves binding of the small (119 amino acid residue) C5 protein to the much larger (377 nucleotide) P RNA subunit. The RNA subunit makes the majority of contacts to the pre-tRNA substrate and contains...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1016/j.jmb.2006.05.001
更新日期:2006-06-30 00:00:00
abstract::Active variant surface glycoprotein (VSG) gene chromatin is preferentially digested by the restriction enzyme HinfI in nuclei of bloodstream variants of Trypanosoma brucei. HinfI sensitivity of VSG gene chromatin is not observed in nuclei of relapse variants in which the VSG gene has been inactivated in situ. Active V...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1016/0022-2836(87)90559-6
更新日期:1987-10-05 00:00:00
abstract::The sigma N class of sigma factors confer upon RNA polymerase the requirement for enhancer-binding activator proteins. The sigma-N (sigma N) protein of Klebsiella pneumoniae was analysed by the assay of purified peptides comprising domains or regions of sigma N defined by proteolysis or by homology alignment, respecti...
journal_title:Journal of molecular biology
pub_type: 杂志文章
doi:10.1006/jmbi.1995.0260
更新日期:1995-05-12 00:00:00
abstract::The oral cavity is accessible to microorganisms, and biofilms are present throughout on hard and soft tissues. The shedding of epithelial cell layers is usually effective for controlling biofilm development on soft tissues. Innate immune mechanisms are not so effective against biofilms on tooth surfaces, and oral hygi...
journal_title:Journal of molecular biology
pub_type: 杂志文章,评审
doi:10.1016/j.jmb.2015.09.022
更新日期:2015-11-20 00:00:00